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Phones sound distorted, especially on VoIP

Started by GusHerb, December 12, 2014, 02:02:43 AM

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GusHerb

Pardon me if I'm not the first person to bring this up here but I didn't come across anything while searching. I've slowly switched our lines to VoIP over the years and finally it came time to do the main line that all of my old phones are on and I've had a problem with them sounding distorted on any VoIP line while speaking into the transmitter. It doesn't matter the provider, nor ATA and it doesn't seem to be the volume, I can adjust that in my ATA's and reducing it doesn't change a thing.
I'd like to figure out what the cause is and find a possible solution, it's very annoying hearing my distorted sidetone and makes me not wanna use any of my old phones.

Thanks all  8)
Jonathan

dsk

Not easy to just give the right answer, but first idea are an impedance mismatch.
You may choose different impedance settings on many ATA's, or you may try to compensate. 

alternative:

The old phone are often optimized for a longer, and not so good line.  Inserting a capacitor (bipolar 150V or more) in series.  2-5 microfarad and a resistor across the capacitor may help.  I would have started with about 100- 200 ohms, and increased step by step up to 600 ohms to test if it helps.

dsk

GusHerb

I think you may be onto the problem, my ATA defaults to 600 ohms impedance, and the next setting it allows is 900 ohms - after I set it to 900 the phones are a touch better but still sounding distorted, some of the G handset transmitters are worse then others, and the F1 transmitter on my 302 sounds almost "perfect". Trying the capacitor and resistor may be my next thing to try in addition to setting the ATA to 900 ohms. Our original landline was approx. 18,000 ft from the CO so I imagine the impedance must've been pretty high.
Jonathan

dsk

You will loose some sound if you use only a resistor, but it will give you an indication on the way to find a solution.
dsk

GusHerb

I took a few of the "offending" phones to my grandmothers house, who still has POTS and found two out of three of them to still sound kinda distorted.
I know quite a few members on here are using at least cable company VoIP, does anyone notice your voice sounding a little distorted on the other persons end?
Jonathan

GusHerb

So I dug out an AE Styleline tonight and found it sounded crystal clear on the VoIP line vs any WE handset with a T1 transmitter I've used. What's different about the Type 41 transmitter that it sounds much better then a T1 transmitter?
Jonathan

Kenton K

Interesting. I've personally never had any problem with T1 transmitters. Have you tried shaking them?

KK

Weco355aman

Hi sorry to say some of the later AE transmitters were better built than the WE/ITT/SC/and others. A E was A different design than  the T1's. Over time the carbon in the T1's become moist and compacted. You can place them in a small box and shake the Hell out of them. This will improve most of them by 25-40 %. Some will never improve. Also the D.C. loop current will have some effect. If you are using REAL phone service you should have better Output, if your using a ATA (vonage type service or cable modem) they will barely work. Most manufactures assume that you will be using a cordless phone.
The only good cordless phone is the one that's in the trash. 
Phil

GusHerb

#8
no amount of shaking has really made a difference, on better ones or worse ones. The newest T1 I have is an Audiosears model from 2003 and it still sounds distorted/fuzzy but isn't as bad as many of the older ones.

Also one of the ones that sounded not so bad on VoIP sounded worse on POTS and one of the ones that sounded worse on VoIP sounds better on POTS.

I guess I've discovered the design shortcomings of the T1 transmitter plus also what age does to them. I may start collecting some AE phones and start using them on our VoIP lines instead. Now I'm curious, is the type 41 a carbon style transmitter as well? And what makes it better? I haven't had much luck finding any info on them.

Jonathan

Kenton K

Can you explain the main differences between AE and We transmitters? I'd be interested in knowing.

Also, if moisture is a problem, is it conceivable to dry the transmitter? Such as in a low temp oven? I'm just throwing out ideas here!

-Ken


Dennis Markham

This is an interesting topic.  Something I never thought about (transmitters sounding worse on VoIP than with POTS).    Some time ago I gave a friend a W.E. Model 500.  On occasion when we speak via the telephone I will know she is using the rotary dial phone because her voice is fuzzy.  I keep planning to bring her a "new" T1 transmitter but haven't yet.  She has Comcast telephone service which of course is VoIP.  I still have a POTS line here.  So I guess the next move is to bring that phone back over here and see if the transmitter sounds better on the POTS line.  In fact, it may not be the T1 at all.

On a side note, I have an uncle, now in his 80's that retired from Michigan Bell a number of years ago.  His hey-day was probably in the late 50's through the early 80's.  He once told me that when installing a phone in a subscribers home (speaking about a later phone with a T1 transmitter)  he would hold the T1 in the palm of his hand, contact side up and then with the other hand hold a screw driver by its tip, then lightly tap the back of the transmitter with the handle of the screw driver.  He said he did this to loosen up the carbon particles in the transmitter.  That would have been when the transmitters were new or maybe a few years old.  Just imagine how the carbon particles have bonded together after all these years.

~Dennis

Kenton K

One more question.

On old solid back transmitters, or the one I am using,, every movement of the transmitter creates noise. I believe this is the carbon granules shifting.

On new transmitters t1, f1, I don't get this noise. Although carbon is sure to still be moving.

Why is that?

Ken

unbeldi

Since the time Kellogg (I believe) introduced the first position-independent transmitter, carbon granules pretty much didn't move around much anymore.  At least they managed to keep that to a minimum as to not affect the electrical characteristics significantly.

dsk

What happens if you shunt the transmitter with a 220 ohms resistor?  That's a trick working on our Norwegian 1934 and 1953 models using Antwerp transmitter capsules.

dsk

GusHerb

Quote from: Dennis Markham on December 30, 2014, 09:39:29 AM
This is an interesting topic.  Something I never thought about (transmitters sounding worse on VoIP than with POTS).    Some time ago I gave a friend a W.E. Model 500.  On occasion when we speak via the telephone I will know she is using the rotary dial phone because her voice is fuzzy.  I keep planning to bring her a "new" T1 transmitter but haven't yet.  She has Comcast telephone service which of course is VoIP.  I still have a POTS line here.  So I guess the next move is to bring that phone back over here and see if the transmitter sounds better on the POTS line.  In fact, it may not be the T1 at all.


I think at least part of the reason they sound worse on VoIP is because VoIP has considerably increased volume over the average POTS line therefore making imperfections more noticeable - at least that's one plausible theory. Ive tested on two POTS lines now and the "trouble" transmitters sound almost as bad as on VoIP.

The first time I ever noticed this was when I gave someone that has Uverse Voice a Trimline and the first time I spoke to her on it she sounded like she was talking into a kazoo almost, her early 90s electronic-transmitter-equipped Trimline she had before sounded perfect.
I still shudder to think about what they did to that Trimline I gave them (and will never give them another!)
Jonathan